The Great Cycle of Life.
The life of an Orthodox Christian can be seen as being composed of five cycles. There is, first of all, the great cycle of life, which embraces the whole life of a man from birth to death, and which consists in liturgical actions which are not repeated, occurring only once in a person’s lifetime. These are Holy Baptism, Holy Chrismation, and the Burial Service. In addition, there also belongs in this great cycle the Sacraments or Sacramental Blessings which bestow special grace for a particular office or vocation with the community. These are Holy Matrimony, the Monastic Tonsure and Holy Orders.
The Daily Cycle.
Another major cycle which involves the entire life of an Orthodox Christian is the daily cycle of prayers and praises offered by the Church, once every twenty-four hours. These services express our remembrance of events which happened at certain hours and contain petitions relevant to these memories.
In antiquity the day was considered to begin at sunset and thus was divided according to the following order. Night began at 6:00 p.m. (according to our reckoning) and was divided into four parts (called watches the time of changing guards): Evening (6:00 p.m. to 9:00 p.m.); Midnight (9:00 p.m. to 12:00 midnight); Cock-crow (12:00 midnight to 3:00 a.m.); and Morning (3:00 a.m. to 6:00 a.m.). Day began at 6:00 a.m. (our reckoning) and it, too, was divided into four watches (or hours). First Hour (6:00 a.m. to 9:00 a.m.); Third Hour (9:00 a.m. to 12:00 noon); Sixth Hour (12:00 noon to 3:00 p.m.); and Ninth Hour (3:00 p.m. to 6:00 p.m.).
Following this ancient pattern, Orthodox Christians begin each portion of the day with common prayer, which has resulted in the following eight Services, customarily divided into three groups: Ninth Hour, Vespers, and Compline; Nocturns (Midnight Service), Matins, and First Hour; Third and Sixth Hours. In addition to this daily pattern, in certain monasteries during certain periods of fasting, each of the Hours is followed by an intermediate Office called the Interhour. Also included in the daily cycle are the Offices for the Blessing of the Table and the Morning and Evening Prayers.
The Divine Liturgy is often included in this daily cycle, normally being served after the Sixth Hour (although, during Fast Periods it is celebrated after Vespers). Often treated as part of the daily cycle, the Divine Liturgy is not prescribed to be celebrated every day (as it is in many cathedrals and monasteries) and in a theological and mystical sense actually stands outside of chronological time since it also serves as a point of contact with the eternal, where its participants (by virtue of their partaking of the Holy Eucharist) are transported to a point outside of time where there is no past, present or future, but only the eternal Now